The head of Russia's space agency said on Tuesday that cosmic radiation was the most likely cause of the failure of a Mars moon probe that crashed to Earth this month, and suggested that a low-quality imported component may have been vulnerable to the radiation.

The unmanned probe was to have gone to the Mars moon of Phobos, taken soil samples and brought them back. But it became stuck in Earth orbit soon after its launch on November 9. It fell out of orbit on January 15, reportedly off the coast of Chile, but no fragments have been found.

Severe embarrassment

The failure was a severe embarrassment to Russia, and space agency head Vladimir Popovkin initially suggested it could have been due to foreign sabotage.

But Russian news agencies on Tuesday quoted him as saying an investigation showed the probable cause was “localised influence of heavily radiated space particles.” Popovkin, speaking in the city of Voronezh where the report was presented to Deputy Prime Minister Dmitry Rogozin, said two units of the Phobos Ground probe's onboard computer system went into an energy-saving “restart” mode, apparently due to the radiation, while the craft was in its second orbital circuit. It was not immediately clear why the units could not be brought out of that mode.

He was quoted as saying that some microchips used on the craft were imported and possibly of inadequate quality to resist radiation. He did not specify where the chips were manufactured. He also said the craft's builder, Moscow-based NPO Lavochkin, should have taken into account the possibility of radiation.

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